Stihl MS311/391 Port Cover Removal

[magicmanar98]

Has anybody successfully removed the port covers on the stihl MS391/311 cylinder? I’m not sure how stihl seals these things on but they’re on there. There’s gotta be a way but I haven’t found it. I appreciate any input. Thanks

 

[alexcagle]

I re-glued one that had popped loose with yamabond #4 a year ago that is still holding......

 

[Justin Taylor]

Has anybody successfully removed the port covers on the stihl MS391/311 cylinder? I’m not sure how stihl seals these things on but they’re on there. There’s gotta be a way but I haven’t found it. I appreciate any input. Thanks

What are you planing on doing?

 

[alexcagle]

Cleaned it first several times with lacquer thinner though.
The cylinder was off the saw, and I put it in my oven at 120º overnight. It's probably high heat epoxy.

 

[magicmanar98]

I re-glued one that had popped loose with yamabond #4 a year ago that is still holding......

I had one pop off too, but the other I can’t get to budge. Been chipping aluminum off working the other side.

 

[magicmanar98]

What are you planing on doing?

Dremel transfers to open it up a bit. I’m pretty good porting intake and exhaust. Not so much on transfers. Covers off will make it easier. I’ve got a machinist at work gonna drop cylinder .020” as stock squish measured .040-.045”.

 

[magicmanar98]

Cleaned it first several times with lacquer thinner though.
The cylinder was off the saw, and I put it in my oven at 120º overnight. It's probably high heat epoxy.

I put a heat gun on it and it didn’t phase it. The one that came off of one side of mine looks like liquid steel or they got the aluminum to bond to each other somehow.

 

[Justin Taylor]

Dremel transfers to open it up a bit. I’m pretty good porting intake and exhaust. Not so much on transfers. Covers off will make it easier. I’ve got a machinist at work gonna drop cylinder .020” as stock squish measured .040-.045”.

Dropping the cylinder on a clamy I need to see some pics

 

[magicmanar98]

Dropping the cylinder on a clamy I need to see some pics

I will this time. If I can ever get this darn cover off! Not gonna try it on new 391 cylinder until I figure out a good way on this 311 cylinder.

 

[rupedoggy]

Huskybill says just take .020 of the cylinder then .020 off the top of the bearing race and seal LOL

 

[Justin Taylor]

Huskybill says just take .020 of the cylinder then .020 off the top of the bearing race and seal LOL

 

[Justin Taylor]

I will this time. If I can ever get this darn cover off! Not gonna try it on new 391 cylinder until I figure out a good way on this 311 cylinder.

And porting a 311 would be a pain in the ass I think

 

[Justin Taylor]

I will this time. If I can ever get this darn cover off! Not gonna try it on new 391 cylinder until I figure out a good way on this 311 cylinder.

Btw there is a pop up piston for the 391 if you didn’t already know

 

[rupedoggy]

Oh don't tell him that. He was doing so good without it.

 

[Justin Taylor]

Oh don't tell him that. He was doing so good without it.

Let’s just hope he doesn’t need it

 

[magicmanar98]

Oh don't tell him that. He was doing so good without it.

Oh no! I gotta have it. Might as well just cut squish to .010”-.012” and see if I can get the piston to fly through the clouds.

 

[magicmanar98]

My dealer said it took 3 tanks of straight gas to lock the 311 motor up, so who knows, the sky’s the limit

 

[Justin Taylor]

My dealer said it took 3 tanks of straight gas to lock the 311 motor up, so who knows, the sky’s the limit

The wrist pin shaved like .030 because the cir clip fell out and it dosent even care on my 311

 

[magicmanar98]

The wrist pin shaved like .030 because the cir clip fell out and it dosent even care on my 311

What kind of bar and chain setup are you using on your 311?

 

[Justin Taylor]

What kind of bar and chain setup are you using on your 311?

20 3/8 .050